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ETSITS101 574vi.ii 



(2011-11) 




Access, Terminals, Transmission and Multiplexing (ATTM); 

System characteristics of receiver equipment installed in 

headends of integrated broadband cable and television 

networks intended to receive broadcast signals in the 

frequency range 470 MHz to 790 MHz 



ETSITS101 574 V1 .1.1 (2011-11) 



Reference 



DTS/ATTM-003017 
Keywords 



cable, CRS 



ETSI 

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ETSI 



ETSITS101 574 V1 .1.1 (2011-11) 



Contents 



Intellectual Property Rights 4 

Foreword 4 

1 Scope 5 

2 References 5 

2.1 Normative references 5 

2.2 Informative references 5 

3 Definitions, symbols and abbreviations 5 

3.1 Definitions 5 

3.2 Symbols 6 

3.3 Abbreviations 6 

4 Background 6 

4.1 Cable System Architecture 6 

4.2 Frequency Allocations & Usage 6 

4.3 Purpose of Cable Headend Receivers 7 

4.4 Methods for Primary Distribution of Television Programming to Cable Headends 7 

5 Headend Receiver Characteristics 7 

5.1 Antenna Characteristics 8 

5.1.1 Parameters for Antenna Installations 8 

5.1.2 Directional Patterns 8 

5.2 Receiver Characteristics 9 

5.3 Resulting Receiver System Characteristics 9 

6 Deployment Scenarios 9 

Annex A (informative): Protection of Cable Headend Receivers 11 

Annex B (informative): Example Link Budget Calculation 13 

History 14 



ETSI 



ETSI TS 101 574 V1.1.1 (2011-11) 



Intellectual Property Rights 



IPRs essential or potentially essential to the present document may have been declared to ETSI. The information 
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found 
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in 
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web 
server ( http://ipr.etsi.org) . 

Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee 
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web 
server) which are, or may be, or may become, essential to the present document. 



Foreword 

This Technical Specification (TS) has been produced by ETSI Technical Committee Access, Terminals, Transmission 
and Multiplexing (ATTM). 



ETSI 



ETSITS101 574 V1 .1.1 (2011-11) 



Scope 



The present document defines system characteristics of the receiving equipment used in cable headends including but 
not limited to receiver noise figure, antenna gain, signal-to-noise ratio, etc. 



References 



References are either specific (identified by date of publication and/or edition number or version number) or 
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the 
reference document (including any amendments) applies. 

Referenced documents which are not found to be publicly available in the expected location might be found at 
http://docbox.etsi.org/Reference . 

NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee 
their long term validity. 

2.1 Normative references 

The following referenced documents are necessary for the application of the present document. 
Not applicable. 

2.2 Informative references 

The following referenced documents are not necessary for the application of the present document but they assist the 
user with regard to a particular subject area. 

[i.l] ETSI TR 102 881 (VI. 1.1): "Access, Terminals, Transmission and Multiplexing (ATTM); Cable 

Network Handbook" . 

[i.2] ETSI EN 300 744: "Digital Video Broadcasting (DVB); Framing structure, channel coding and 

modulation for digital terrestrial television" . 

[i.3] United States Code of Federal Regulations, Title 47, Part 15, Subpart H: "Television Band 

Devices". 

[i.4] FCC 10-174: "Second Memorandum Opinion and Order in the Matter of Unlicensed Operation in 

the TV Broadcast Bands", September 23, 2010. 

[i.5] ETSI TS 102 639 (April 2009): "Access and Terminals, Transmission and Multiplexing 

(ATTM);Third Generation Transmission Systems for Interactive Cable Television Services - IP 
Cable Modems". 



3 Definitions, symbols and abbreviations 

3.1 Definitions 

For the purposes of the present document, the following terms and definitions apply: 
cable drop: small gauge coaxial cable that connects the customer premises to a tap 

NOTE: This may contain additional information. 
fibre node: device which performs a media conversion between a fibre link and a coaxial link in an HFC network 



ETSI 



6 ETSI TS 1 01 574 V1 .1 .1 (201 1-11) 

headend: cable operator facility where video signals are received and launched into the cable access network 

tap: device having coaxial cable connections that splits downstream input RF signals among various output connections 

3.2 Symbols 

For the purposes of the present document, the following symbols apply: 



MHz 


megahertz 


dB 


decibel(s) 


m 


meter(s) 


km 


kilometer(s) 


dBm 


decibel referenced to 1 milliwatt 


kW 


kilowatt 



3.3 Abbreviations 

For the purposes of the present document, the following abbreviations apply: 

COFDM Coded Orthogonal Frequency Division Multiplexing 

DVB-T Digital Video Broadcast - Terrestrial 

FCC United States Federal Communications Commission 

HFC Hybrid Fibre/Coax 

MVPD Multi-channel Video Programming Distributor 

NCTA National Cable & Telecommunications Association 

OOB Out-Of-Band 

RF Radio Frequency 

TV television 

TVBD Television Bands Device 



4 Background 

4.1 Cable System Architecture 

Integrated broadband cable and television networks support delivery of a wide range of digital entertainment and 
informational programming via the use of a hybrid fibre/coaxial network. As described more fully in [LI], the typical 
cable system consists of a "headend" facility and a distribution network. The headend facility is where the cable system 
interconnects with video content distribution sources, the public switched telephone network, and the Internet. The 
distribution network (plant) typically consists of optical fibre connectivity to "fibre nodes" located in proximity to 
residential neighborhoods, followed by coaxial cable connecting the fibre nodes to customer premises equipment. The 
coaxial portion of the plant is a tree and branch structure, often with a main coaxial line (having signal-boosting 
amplifiers spaced periodically) and individual cable drops that connect to the main line via "taps". Once the cable drop 
reaches the customer premises, it is often split to reach multiple customer premises devices. 

4.2 Frequency Allocations & Usage 

Digital television signals are carried on the cable plant using similar channelization (though different modulation) and 
similar spectrum as is used for terrestrial broadcast. Due to the physically contained nature of the spectrum in the cable 
plant, there is no need to have gaps (white spaces) between programme channels, and as a result all of the channels are 
occupied in carrying content. 

Whilst there are country-by-country, operator-by-operator, and even system-by-system differences in plant operations, 
for carrying programming content from the headend to the customer, the contiguous block of spectrum beginning 
typically at 80,6 MHz and running up to 862 MHz (with equipment capable of supporting operation up to 1 GHz as 
defined by ETSI and CENELEC standards, including [L5]) is utilized. This results in more than 90 channels, each of 
8 MHz, all of which are utilized continuously to provide a wide variety of services including linear television 
programming, video on demand, broadband Internet and telephony. 



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7 ETSI TS 1 01 574 V1 .1 .1 (201 1 -1 1 ) 

4.3 Purpose of Cable Headend Receivers 

The cable operator provides a variety of television programme channels to its customers. In some cases the channels are 
selected in order to appeal to customer interests, in other cases local and/or national regulations may require the cable 
operator to carry certain channels. 

In order for the cable operator to provide television channels to its customers, the cable headend needs to have means to 
receive television programming content from a variety of sources, some may be international television channels, others 
may be national or regional channels, and still others may be local channels. The distribution of programming content 
by the content producer to the content distributors (e.g. cable operators) is sometimes referred to as "primary 
distribution" . The cable system operator will establish reliable (and often redundant) means by which to receive each of 
the programming channels that will be distributed over the cable plant. 

4.4 Methods for Primary Distribution of Television Programming 
to Cable Headends 

Cable system operators employ a variety of technologies to receive television programming at their headend facilities 
for subsequent distribution over the cable plant. In many cases, a cable operator will utilize multiple technologies in 
order to receive the full set of programming that will be distributed over their cable plant, as well as to provide 
redundancy. 

For reception of local and distant "off-air" broadcasts (DVB-T) [i.2], cable operators frequently utilize a high gain 
directional antenna and professional receiver. These systems can be used for the main reception of video programming 
from a local broadcaster, and are also commonly used as a backup when other technologies are employed. 

Other technologies include satellite downlink equipment (commonly used for international content), and dedicated 
optical fibre or point-to-point microwave links (used when the content source is located in relatively close proximity to 
the cable headend). 



5 Headend Receiver Characteristics 

Cable headends are facilities that have a variety of functions as the central source of services in a cable television 
network. Among them is the acquisition and distribution of video signals. In many cases, the Cable headend is equipped 
with means for the primary (and/or backup) reception of television programmes via terrestrial distribution channels. 
Equipment used for terrestrial reception in Cable headends typically consists of antennas with high gain and elaborated 
directional characteristics that are mounted on towers in elevated positions. Signals are processed by professional 
receivers with technical specifications meeting the requirements of a reliable and low-maintenance network operation. 
The locations of antenna towers and signal processing equipment may or may not be geographically co-located. They 
could be located at some distance and be connected via a dedicated point-to-point link. Figure 1 depicts an example 
architecture of cable headend components. For simplification reasons, only a co-located case is shown where the 
antenna tower is connected to the receiver by a feeder cable. The illustration is not meant to imply the usage of any 
particular component, e.g. antenna type. 



ETSI 




Antenna 



Antenna mast 



Feeder 



Terrestrial 

Cable Headend 

Receiver 



ETSITS101 574 V1 .1.1 (2011-11) 




HFC 

Network 

Processing 



Figure 1: Signal contribution in cable headends 



5.1 



Antenna Characteristics 



5.1.1 Parameters for Antenna Installations 

Table 1 gives the main parameters required for antenna installations used in Cable headend receivers. 

Table 1 : Antenna Parameters 



Parameter 


Typical Value 


Value Range 


Antenna gain 


10dB 


8dBto12dB; 
up to > 20 dB with 
sophisticated 
antenna 
configurations 


Mounting height 


20 m 


1 2 m to 35 m 



5.1 .2 Directional Patterns 

Figure 2 depicts a sample directional pattern for a log periodic antenna typically used in Cable headend receivers. 




Log Periodic Antenna elevation pattern Log Periodic Antenna azimuth pattern 



Figure 2: Sample Antenna Directional Pattern 



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ETSITS101 574 V1 .1.1 (2011-11) 



5.2 



Receiver Characteristics 



Table 2 gives the main parameters required for professional receivers used in Cable headend installations. 

Table 2: Receiver Characteristics 



Parameter 


Typical Value 


Value Range 


Input level 


-65 dBm to -25 dBm 


-80 dBm to -10 dBm 


Modulation 


COFDM 
(DVB-T/T2) 




Noise figure 


5dB 


3dBto8dB 


Suppression of OOB signals 


40 dB (for adjacent carriers) 
50 dB to 60 dB (for others) 





5.3 Resulting Receiver System Characteristics 

The combination of high gain antennas and professional receiving equipment with high sensitivity and noise 
performance allow for terrestrial receivers installed at Cable headends to acquire and demodulate TV station signals that 
are well beyond the service area of the TV transmitter as defined for a residential terrestrial receiver. An example link 
budget, which illustrates this point is provided in annex B. 



6 Deployment Scenarios 

System characteristics of headend receivers as analyzed in clause 5 allow Cable headends to be located outside the area 
in which a TV transmitter is able to serve residential equipment and still receive terrestrial broadcasting services. 
Redistribution of those TV services through the cable television network even further enlarges the geographical area 
where customers are able to consume the TV service. Figure 3 depicts a typical scenario for cable headend installations 
in- and outside the residential service area of a terrestrial transmitter. Subscriber X, located outside the GE06 area, 
consumes the broadcast TV services by way of a professional cable headend receiver, thus extending the serving area of 
the terrestrial broadcaster. 



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10 



ETSITS101 574 V1 .1.1 (2011-11) 



Cable Headend 



Subscriber X 



Cable Headend 
O 




O o 



Terrestrial 



® 



Transmitter 



° o 

o o ° 




Cable Headend 

I 
I 



O ^^ 



Cable Headend 






N s Residential equipment 



N x serving area 



Professional equipment 
serving area 



Figure 3: Cable headends in- and outside the residential equipment serving area 

of a terrestrial TV transmitter 



ETSI 



11 ETSI TS 1 01 574 V1 .1 .1 (201 1 -1 1 ) 



Annex A (informative): 

Protection of Cable Headend Receivers 

In many regions, the terrestrial television broadcast bands are subject to licensing, and license holders are protected 
from interfering signals within a defined area surrounding the broadcast antenna. The outer boundary of the protected 
area is known as the broadcast contour for the station. The licensing authority seeks to assign frequency licenses to 
stations to ensure that receiver locations within the broadcast contour for each station are assured that they can receive 
the station's signal without disruptive interference from other users of that frequency or adjacent frequencies. In order to 
achieve this, the licensing authority ensures that other licensees for that frequency and the adjacent frequencies are a 
sufficient distance away from the broadcast contour of the station in question. For each frequency in the broadcast band, 
the result from a geographic perspective can be a set of "islands" of licensed use within a sea of "white space". 
Conversely, any selected geographical location may be within the broadcast contour for some number of stations, each 
transmitting on its licensed frequency, and the remaining frequencies are essentially unused. 

In certain regions these unused frequencies, or "white spaces" are currently planned to be used for 
radiocommunications, primarily for data services. Such usage is expected to be unlicensed on a non-exclusive and non- 
protected basis. Therefore it will be subject to rules that, for example, require users to avoid frequencies that are in use 
by the licensed broadcasters. 

In the United States, for example, the US Federal Communications Commission (FCC) has defined rules allowing 
unlicensed "Television Bands Devices" (TVBDs) to operate on most frequencies of the television broadcast band, 
providing that they consult a "geo-location database" in order to determine which frequencies are available for use in 
their present location. The geo-location database therefore contains data about the licensed users of the television band, 
along with the geographical information about the broadcast contour for each licensee. In addition, the FCC has allowed 
that certain other areas can be protected via registration with the geo-location database. For example, the FCC has 
allowed that performance venues that use low-power wireless microphones can be registered. Furthermore, certain 
professional sites which receive broadcast transmissions, but which fall outside the broadcast contour for a licensed 
terrestrial broadcaster, can be registered and provided with a protection contour in order to assure continued reliable use 
of the terrestrial broadcast signal. 

The FCC has determined that such sites, which include cable headends, shall be protected as follows [i.3], (Part 15, 
Section 712, paragraph b): 

"TV translator, Low Power TV (including Class A) and Multi-channel Video Programming Distributor (MVPD) 
receive sites. MVPD, TV translator station and low power TV (including Class A) station receive sites located 
outside the protected contour of the TV station(s) being received may be registered in the TV bands database if they 
are no farther than 80 km outside the nearest edge of the relevant contour(s). Only channels received over the air and 
used by the MVPD, TV translator station or low power/Class A TV station may be registered. TVBDs may not 
operate within an arc of ±30 degrees from a line between a registered receive site and the contour of the TV station 
being received in the direction of the station's transmitter at a distance of up to 80 km from the edge of the protected 
contour of the received TV station for co-channel operation and up to 20 km from the registered receive site for 
adjacent channel operation, except that the protection distance shall not exceed the distance from the receive site to 
the protected contour. Outside of this ±30 degree arc, TVBDs may not operate within 8 km from the receive site for 
co-channel operation and 2 km from the receive site for adjacent channel operation. For purposes of this section, a 
TV station being received may include a full power TV station, TV translator station or low power TV/Class A TV 
station." 



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ETSITS101 574 V1 .1.1 (2011-11) 



Additionally, the FCC has allowed for operators of existing sites located more than 80 km from the edge of the 
broadcast contour to apply for a waiver of the rules, so that those sites can be registered in the geo-location database as 
well[i.4]: 

"42. We recognize that there are cable headends that receive TV station signals located at distances beyond 80 km 
from the edge of a television station's protected service contour and understand NCTA's concern for possible 
disruption service to cable subscribers. These same considerations would apply to other MVPDs and to TV 
translator, low power TV and Class A TV stations that re-transmit programming from another TV station. We do not 
believe that the requested change would have significant impact on the availability of TV white space because these 
facilities are generally in remote areas where many channels will be available for white space devices. However, we 
also recognize that parties may wish to have an opportunity to review such requests to confirm the assessment. We 
are therefore providing that current MVPD operators, TV translator, low power TV and Class A TV stations with 
receive sites located beyond the 80 km co-channel protection distance in the rules may apply for a waiver of that 
distance during a period that will end 90 days after the effective date of the rules adopted herein. Such waiver 
requests would also involve shifting the 20 km adjacent channel protection distance so that it is measured from the 
actual receive site. We will then issue a public notice requesting comment on requests we receive and issue 
decisions. MVPD operators and TV translator, low power TV and class a TV stations that commence operation in 
the future with receive sites located beyond the co-channel and adjacent protection distances may apply for a waiver 
of those distances within 90 days of commencing operation. Following receipt of such request(s), we will then issue 
a public notice asking for comment on the request(s) and issue decision(s)." 

Figure A.l illustrates the protection regions defined by the FCC for professional receive sites. 



Headend Receive 
-8 km-^1 Antenna 

l^-^l 2 km 




[^ — 20 km — ►! 




| Adjacent and Co-channel Protection 
I Co-channel Protection 



Figure A.1: Adjacent and Co-channel Protection Regions Defined by 
the US Federal Communications Commission 



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13 



ETSITS101 574 V1 .1.1 (2011-11) 



Annex B (informative): 
Example Link Budget Calculation 



For a case of a terrestrial broadcaster operating at 630 MHz, transmitting at 70 dBm (10 kW), and received by a cable 
headend receiver at a distance of 200 km utilizing the typical values listed above, the following is an example link 
budget. 

Table B.1: Example Link Budget 



Attribute 


Value 


Notes 


Transmit Power 


70 dBm 




Propagation Loss 


-127 dB 


Tx Antenna Height = 200 m 
Rx Antenna Height = 20 m 
Suburban terrain 
Link Distance = 200 km 
Frequency = 630 MHz 


Receive Antenna Gain 


10dB 




Receiver Cabling 


-3dB 




Receiver Level 


-50 dBm 





The resulting receive level is well within the typical range for receiver input levels. 



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14 



ETSITS101 574 V1 .1.1 (2011-11) 



History 



Document history 


VI. 1.1 


November 2011 


Publication 



























ETSI